ttg35fort

iTrader: (2)

I don't think so. Do you have T-clamps or work type clamps? Some people have had problems with T-clamps when the ends of the pipes are not sufficiently rolled. Anyway, that is a really, really long shot based on the description of your problem. If that were the problem, it should be popping up alot more.

If you checked all of your wiring, especially your grounds, and it is not an issue with your spark plugs, I would lay odds it is in your fuel return system. If it were me, I would configure the fuel return system like AAM's system as shown in the link I sent you. If your new fuel rails won't fit, then borrow an intake plenum from someone that will clear the fuel rails.

If you cannot find one locally, I have a VQ35DE intake plenum. I was not planning on selling it, but I will let you borrow it. I'll ask for a deposit just to make sure I get it back. I live in the West Palm area. If you want to make a trip up to borrow it, let me know.

streetzlegend

iTrader: (2)

Sounds good, thanx. First im going to change the plugs (ill do this on friday), raise the boost back to 20, if problem continues at 20 then id have to look elsewhere for problems, like fuel.

Id have to look up how the maxima guys rig up the RWD manifold on our FWD vq35de since it does run into the hood, I believe they have to cut or modify the manifold somehow, and in that case, I wouldnt be able to borrow yours ofcourse, and not sure if im ready to buy it yet. We'll see on friday. ill keep you updated, n thanx again

rcdash

iTrader: (18)

Reversion due to excess pre-turbine backpressure? Also if your W/M injection is boost and rpm driven you may be blowing out your spark with too much injection. You could try to taper that a bit.

streetzlegend

iTrader: (2)

What would cause excessive pre-turbine pressure?

rcdash

iTrader: (18)

A small turbine, restrictive exhaust, a small exhaust manifold... basically running more boost than the turbo system can handle. By the way, I run 2 steps colder than stock and no misfires...

streetzlegend

iTrader: (2)

Will a restriction after the turbo such as muffler cause such increase in backpressure? Or only preturbine excessive pressure will cause reversion.

I would assume a restrictive muffler will just cause boost pressure drop, but dont know if it would cause reversion

str8dum1

iTrader: (11)

no way he's blowing out his spark with that lil meth nozzle, esp with that tiny spark plug gap.

Its only a 440cc nozzle. I'm running at least a 600cc (9.5 gph) nozzle (might be bigger) on mine at less boost.

Only feasible if his pump is taking a **** and is not atomizing his spray. I'd pull that out of the equation for now anyhow.

rcdash

iTrader: (18)

Sounds good. YOU can help me pick a nozzle this Saturday!

streetzlegend

iTrader: (2)

Yea i seriously doubt the meth is causing spark blowout. I also constantly test the pump and also check if the line is cracked (since it has cracked twice in a period of 3 years). The pump is working perfectly they are really reliable, iv been running one as a scavange pump for my oil for those 3 years and no issue. So im ruling that out.

rcdash

iTrader: (18)

Well post-turbine backpressure will lead to pre-turbine pressure increase as well. You could try running without the muffler, but it's usually cats that are most restrictive (if you have them). How big is your turbo? Can you post the compressor and turbine flow maps?

streetzlegend

iTrader: (2)

I see, well in my setup I have dont have any cats or even resonators. all I have is the muffler after the turbo (Dynomax Superturbo 3" in/out) which I think its really restrictive.

Although holset does not release flow maps, this might be accurate:


Exhaust housing is 12cm with t3 inlet and 3" outlet, and compressor wheel I think is 54mm with 4" inlet and 2.5" outlet.,

athenG

iTrader: (2)

With a VQ30 which is about 182 cid and and assuming 2psi lost on the piping/intercooler, then you will need about 1.31bar (19psi) to hit 1.17bar on the manifold (17psi). After doing the numbers on a 182cid (3.0L) engine, you will need a turbo that can pump at least 44lbs/min at 6200rpm. If you map is accurate then your turbo is a little small and way past its efficiency range at 6200rpm and 2.3bar. At 17+psi you need at least a 60-1.

Edit: I looked at the map again and it is not terribly bad as I initially thought.. It will be nice to stay within the middle of the map though...

streetzlegend

iTrader: (2)

If thats the case, the map might not be accurate, reason being is that there are guys running this turbo at 27+ psi (4 bangers @ 400-550whp), based on alot of searching I have done, it is said the turbo flows 60lbs/min (dont kno at what rpm).

Either way, I think for now, I am going to stick with 15psi. I am going to upgrade my charge piping and intercooler. I have alot of pressure drop, a 13psi spring gives me about 5-6psi (not good), and this is getting the WG reference from the turbo. Thats about 8psi of pressure drop, mostly due to the intercooler perhaps and a few silicone bends (that might be getting pinched, ill have to see. I have had the same chargepiping setup since day one (3 years ago), so its probably overdue for an upgrade.

ttg35fort

iTrader: (2)

60 lbs/min is a maximum flow rate, and is not tied to a specific rpm. In other words, at whatever rpm your engine needs 60 lbs/min, the turbo should be able to provide assuming you have enough exhaust gas flow at that point to turn the turbines fast enough. That rpm at which your engine starts consuming 60 lbs/min. will primarly depend on the engine's displacement and the boost setting. The rpm will be inversely related to these.

streetzlegend

iTrader: (2)

Thanx for clearing that up for me.

Note: just to point it out, my intercooler is 26" x 5.5" x 2.25"

athenG

iTrader: (2)

+1 you cant compare a 4 banger vs a 6cyl because the bigger displacement will consume more air than a smaller engine at a given rpm. That is why a turbo should always be matched to the engine displacement and power level expectation. I think that turbo is great for 4cyl and high boost but may choke on a V6 and

streetzlegend

iTrader: (2)

Yea thats probably right, although the turbos from factory are mounted on v6cummings with stock 19psi, they run them to about near 30psi. but ofcourse they only rev to what, 3k rpm? so your right, I have been considering an HX40 since it flows alot more, but for now i'll enjoy what I have and keep it at max 15psi.

ttg35fort

iTrader: (2)

A bigger intercooler will help in the overall scheme of things, but I don't think it will fix your particular issue at 6k rpm in 2nd gear. Now I could be wrong, but imo, if it were an air intake/boost issue, and nothing else other than the size of the intercooler is wrong, the issue would be popping up elsewehre, and not onty at 6k rpm in 2nd gear.

IF (and I mean only if) the wiring and spark plugs have been eliminated as potential issues, and there are no issues with boost creep or boost leak, then the fuel retun system is the most likely candidate.

Anyway, if you are happy with your present boost level, then it really becomes a non-issue.

streetzlegend

iTrader: (2)

Update:

So i changed the plugs, I did have 1step colder already as I previously mentioned but i put in a new set, I gapped them at .030 and have my ignition at 16v (same voltage i had before). I did a few little things here and there, I had the injectors grounded on the same wire as the voltage booster device (which is a pretty thick wire that goes to the battery, so I just ran seperate grounds for the injector and the device. changed a few bolts for the upper manifold (which weird thing was that after starting the car, my idle and part throttle was very rich so I had to retune, perhaps I had a vac/boost leak at the manifold from the old bolts/stud not providing enough torque since it was stripped)

I did a few 2nd gear runs and did not feel a misfire or hesitation, took the car all the way to 6200 and nothing. this was at 15psi in 2nd gear, I let the auto get into 3rd and instantly pulled hard and boost jumped to 17psi. The car feels pretty strong now. Perhaps is was the grounds, or the old plugs had been through too much meth (i had a 10gph nozzle before which was overkill, and had dipped the AFR into the 9's alot). The base of the plug where the threads are were basically black, the ground straps were like in the pic on the 1st page.

So. it seems to be solved, for now I am going to keep the boost where it is, and next, upgrade IC and piping from IC to motor.

ttg35fort

iTrader: (2)

^^^^^

Glad it is solved. Great job!